Orthodontic appliances with elastic segments

ABSTRACT

Improved orthodontic appliances, along with related systems and methods, are provided. In one aspect, an orthodontic appliance is provided. The appliance includes a plurality of discrete shell segments, each including one or more cavities shaped to receive at least portions of teeth. The discrete shell segments are joined by an elastic material to form a single appliance shell.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/935,268, filed Sep. 26, 2022, which is a continuation of U.S. patentapplication Ser. No. 14/610,027, filed Jan. 30, 2015, now U.S. Pat. No.11,497,586, issued Nov. 15, 2022, which claims the benefit of U.S.Provisional Application No. 61/969,023, filed Mar. 21, 2014, which areincorporated herein by reference in their entireties.

BACKGROUND

Orthodontic procedures typically involve repositioning a patient's teethto a desired arrangement in order to correct malocclusions and/orimprove aesthetics. To achieve these objectives, orthodontic appliancessuch as braces, retainers, shell aligners, and the like can be appliedto the patient's teeth by an orthodontic practitioner. The appliance isconfigured to exert force on one or more teeth in order to effectdesired tooth movements. The application of force can be periodicallyadjusted by the practitioner (e.g., by altering the appliance or usingdifferent types of appliances) in order to incrementally reposition theteeth to a desired arrangement.

In some instances, however, current orthodontic appliances may not beable to effectively generate the forces needed to achieve the desiredtooth repositioning, or may not afford sufficient control over theforces applied to the teeth. Additionally, the rigidity of some existingappliances may interfere with the ability of the appliance to be coupledto the patient's teeth and may increase patient discomfort.

SUMMARY

Improved orthodontic appliances, as well as related systems and methods,are provided. An orthodontic appliance can be designed to be worn on apatient's teeth and include a plurality of discrete shell segmentsjoined by an elastic material. The appliances described herein provideenhanced control over forces exerted onto the teeth, thus enablingimproved orthodontic treatment procedures.

Accordingly, in one aspect, an orthodontic appliance includes aplurality of discrete shell segments, each including one or morecavities shaped to receive at least portions of teeth. The discreteshell segments are joined by an elastic material to form a singleappliance shell.

Other objects and features of the present invention will become apparentby a review of the specification, claims, and appended figures.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1A illustrates a tooth repositioning appliance, in accordance withmany embodiments.

FIG. 1B illustrates a tooth repositioning system, in accordance withmany embodiments.

FIG. 2 illustrates a method of orthodontic treatment using a pluralityof appliances, in accordance with many embodiments.

FIG. 3A illustrates a segmented orthodontic appliance, in accordancewith many embodiments.

FIG. 3B illustrates the appliance of FIG. 3A placed over the teeth of apatient.

FIG. 3C illustrates the appliance of FIG. 3B after tooth repositioninghas occurred.

FIG. 4 illustrates another segmented orthodontic appliance, inaccordance with many embodiments.

FIG. 5 illustrates a segmented orthodontic appliance with shape memoryproperties, in accordance with many embodiments.

FIGS. 6A and 6B illustrate methods for creating an orthodonticappliance, in accordance with many embodiments.

FIGS. 7A through 7D illustrate fabrication of an orthodontic appliance,in accordance with many embodiments.

FIG. 8 illustrates a method for digitally planning an orthodontictreatment, in accordance with many embodiments.

FIG. 9 is a simplified block diagram of a data processing system, inaccordance with many embodiments.

DETAILED DESCRIPTION

The orthodontic appliances described herein, along with related systemsand methods, can be employed as part of an orthodontic treatmentprocedure in order to reposition one or more teeth, maintain a currentposition of one or more teeth, or suitable combinations thereof. Anorthodontic appliance can include a plurality of discrete shellsegments, each including a plurality of cavities shaped to receive atleast portions of a patient's teeth, that are joined by elastic material(also referred to herein as “elastics”) to form a single applianceshell. The geometry, configuration, and material properties of the shellsegments and/or elastic material can be selected to at least partiallycontrol the magnitude and direction of the forces applied to the teethby the appliance. In some instances, the applied forces are provided inwhole or in part as a result of the elastic material joining thesegments. In contrast to existing orthodontic approaches, whichtypically employ a single appliance shell with homogeneous and/orcontinuous material properties, the material properties (e.g.,stiffness) of the appliances described herein can be varied via theelastics, thus, e.g., affording different force application to differentteeth of the patient's arch and, in some instances, more preciseapplication or delivery of one or more forces to teeth. Additionally,the segmented appliances disclosed herein may in some instancesaccommodate larger tooth movements than conventional unsegmentedappliances, thus reducing the number of different appliances needed tocomplete a course of orthodontic treatment. Furthermore, the combinationof relatively rigid shell segments and relatively compliant elasticjoining materials can in some instances improve the appliance fit andreduce patient discomfort, while maintaining the appliance's ability toexert forces sufficient for repositioning teeth.

Thus, in one aspect, an orthodontic appliance includes a plurality ofdiscrete shell segments, each including one or more cavities shaped toreceive at least portions of teeth. The discrete shell segments arejoined by an elastic material to form a single appliance shell. Theappliance shell may be a continuous appliance shell.

In some instances, a stiffness of the plurality of discrete shellsegments is greater than a stiffness of the elastic material. Shellsegments may vary in design. In some instances, one or more of theplurality of discrete shell segments forming an appliances may beconfigured to receive only a single tooth. In some embodiments, one ormore of the plurality of discrete shell segments may be configured tospan or receive a plurality of teeth. An appliance may include segmentsof the same or different types with respect to a number of teeth spannedor received by the segment. For example, an appliance may include somediscrete shell segment(s) that span or receive a single tooth, and somediscrete shell segment(s) that span or receive a plurality of teeth.

In many embodiments, the elastic material comprises a plurality ofdiscrete elastic segments. The plurality of discrete elastic segmentscan be positioned between the plurality of discrete shell segments. Forexample, the plurality of discrete elastic segments can each bepositioned near or adjacent to an interproximal region between teethwhen the appliance is worn on the teeth. In many embodiments, theplurality of discrete shell segments are embedded in the elasticmaterial.

In another aspect, an appliance as described herein may be included in aseries of appliances so as to provide an orthodontic system forpositioning teeth. Such an orthodontic system can include a plurality oforthodontic appliances each comprising a shell including a one or morecavities shaped to receive at least portions of teeth. The appliancesmay be successively worn by a patient to move one or more teeth from afirst arrangement to a second arrangement. One or more of the appliancescan include a segmented appliance as described herein. For example, asegmented appliance of a system can include a plurality of discreteshell segments, each including one or more cavities shaped to receive atleast portions of teeth; and an elastic material joining the pluralityof discrete shell segments to form a single appliance shell. Theplurality of appliances can include a first appliance and a secondappliance having different elastic properties relative to each other.

An appliance can be designed or fabricated with a desired stiffness orso as to impart a desired tooth movement force or set of forces to thepatient's teeth. In some instances, a stiffness of the plurality ofdiscrete shell segments is greater than a stiffness of the elasticmaterial. At least some of the plurality of discrete shell segments maybe configured to receive a single tooth. Alternatively or in addition,at least some of the plurality of discrete shell segments may beconfigured to receive a plurality of teeth.

In many embodiments, the elastic material of an appliance comprises aplurality of discrete elastic segments. The same or similar elasticmaterial may be utilized between various different segments, ordifferent elastic materials may be utilized. Herein, similar elasticmaterial may, for example, refer to a different elastic material, theelastic properties of which have variations of no more than 5% from thecorresponding values of the properties of the other elastic material, orvariations of no more than 10% from the corresponding values of theproperties of the other elastic material. The plurality of discreteelastic segments can be positioned between the plurality of discreteshell segments. For example, the plurality of discrete elastic segmentscan each be positioned near or adjacent to an interproximal regionbetween teeth when the appliance is worn on the teeth. The plurality ofdiscrete shell segments can be coupled to the elastic material in avariety of ways suitable for use in orthodontic positioning as describedherein. Discrete shell segments may be embedded in the elastic material,elastic material may be embedded in material of the shell segments, or acombination thereof. Discrete shell segments and elastic material mayalso be glued, thermoformed together, mechanically connected, stitched,riveted, weaved together, or connected in any other manner such that thealigner is suitable for use as described herein.

In another aspect, a method for creating an orthodontic appliance isincluded herein. A method of creating or fabricating an appliance caninclude providing a shell, in whole or in part, including one or morecavities shaped to receive at least portions of teeth. In some instancesthe shell is fabricated into a plurality of discrete shell segments, andthen joined together using elastic material, thereby forming a single,or continuously assembled appliance shell. In some instances, the shellor portion thereof is fabricated and then can be separated into aplurality of discrete shell segments, each including one or morecavities shaped to receive at least portions of teeth. The discreteshell segments can be joined using an elastic material, thereby forminga single, or continuous assembly, appliance shell.

In many embodiments, a stiffness of the plurality of discrete shellsegments is greater than a stiffness of the elastic material. At leastsome of the plurality of discrete shell segments may be configured toreceive a single tooth. Alternatively or in addition, at least some ofthe plurality of discrete shell segments may be configured to receive aplurality of teeth.

In many embodiments, the elastic material comprises a plurality ofdiscrete elastic segments. Joining the plurality of discrete shellsegments using an elastic material can include positioning the pluralityof discrete elastic segments between the plurality of discrete shellsegments. For example, the plurality of discrete elastic segments caneach be positioned near or adjacent to an interproximal region betweenteeth when the appliance is worn on the teeth. In many embodiments,joining the plurality of discrete shell segments using the elasticmaterial can include embedding the plurality of discrete shell segmentsin the elastic material.

Turning now to the drawings, in which like numbers designate likeelements in the various figures, FIG. 1A illustrates an exemplary toothrepositioning appliance or aligner 100 that can be worn by a patient inorder to achieve an incremental repositioning of individual teeth 102 inthe jaw. The appliance can include a shell (e.g., a continuous polymericshell or a segmented shell) having teeth-receiving cavities that receiveand resiliently reposition the teeth. An appliance or portion(s) thereofmay be indirectly fabricated using a physical model of teeth. Forexample, an appliance (e.g., polymeric appliance) can be formed using aphysical model of teeth and a sheet of suitable layers of polymericmaterial. In some instances, a physical appliance is directlyfabricated, e.g., using rapid prototyping fabrication techniques, from adigital model of an appliance. An appliance can fit over all teethpresent in an upper or lower jaw, or less than all of the teeth. Theappliance can be designed specifically to accommodate the teeth of thepatient (e.g., the topography of the tooth-receiving cavities matchesthe topography of the patient's teeth), and may be fabricated based onpositive or negative models of the patient's teeth generated byimpression, scanning, and the like. Alternatively, the appliance can bea generic appliance configured to receive the teeth, but not necessarilyshaped to match the topography of the patient's teeth. In some cases,only certain teeth received by an appliance will be repositioned by theappliance while other teeth can provide a base or anchor region forholding the appliance in place as it applies force against the tooth orteeth targeted for repositioning. In some cases, many or most, and evenall, of the teeth will be repositioned at some point during treatment.Teeth that are moved can also serve as a base or anchor for holding theappliance as it is worn by the patient. Typically, no wires or othermeans will be provided for holding an appliance in place over the teeth.In some cases, however, it may be desirable or necessary to provideindividual attachments or other anchoring elements 104 on teeth 102 withcorresponding receptacles or apertures 106 in the appliance 100 so thatthe appliance can apply a selected force on the tooth. Exemplaryappliances, including those utilized in the Invisalign® System, aredescribed in numerous patents and patent applications assigned to AlignTechnology, Inc. including, for example, in U.S. Pat. Nos. 6,450,807,and 5,975,893, as well as on the company's website, which is accessibleon the World Wide Web (see, e.g., the url “invisalign.com”). Examples oftooth-mounted attachments suitable for use with orthodontic appliancesare also described in patents and patent applications assigned to AlignTechnology, Inc., including, for example, U.S. Pat. Nos. 6,309,215 and6,830,450.

FIG. 1B illustrates a tooth repositioning system 110 including aplurality of appliances 112, 114, 116. Any of the appliances describedherein can be designed and/or provided as part of a set of a pluralityof appliances used in a tooth repositioning system. Each appliance maybe configured so a tooth-receiving cavity has a geometry correspondingto an intermediate or final tooth arrangement intended for theappliance. The patient's teeth can be progressively repositioned from aninitial tooth arrangement to a target tooth arrangement by placing aseries of incremental position adjustment appliances over the patient'steeth. For example, the tooth repositioning system 110 can include afirst appliance 112 corresponding to an initial tooth arrangement, oneor more intermediate appliances 114 corresponding to one or moreintermediate arrangements, and a final appliance 116 corresponding to atarget arrangement. A target tooth arrangement can be a planned finaltooth arrangement selected for the patient's teeth at the end of allplanned orthodontic treatment. Alternatively, a target arrangement canbe one of many intermediate arrangements for the patient's teeth duringthe course of orthodontic treatment, which may include various differenttreatment scenarios, including, but not limited to, instances wheresurgery is recommended, where interproximal reduction (IPR) isappropriate, where a progress check is scheduled, where anchor placementis best, where palatal expansion is desirable, where restorativedentistry is involved (e.g., inlays, onlays, crowns, bridges, implants,veneers, and the like), etc. As such, it is understood that a targettooth arrangement can be any planned resulting arrangement for thepatient's teeth that follows one or more incremental repositioningstages. Likewise, an initial tooth arrangement can be any initialarrangement for the patient's teeth that is followed by one or moreincremental repositioning stages.

FIG. 2 illustrates a method 200 of orthodontic treatment using aplurality of appliances, in accordance with many embodiments. The method200 can be practiced using any of the appliances or appliance setsdescribed herein. In act 210, a first orthodontic appliance is appliedto a patient's teeth in order to reposition the teeth from a first tootharrangement to a second tooth arrangement. In act 220, a secondorthodontic appliance is applied to the patient's teeth in order toreposition the teeth from the second tooth arrangement to a third tootharrangement. The method 200 can be repeated as necessary using anysuitable number and combination of sequential appliances in order toincrementally reposition the patient's teeth from an initial arrangementto a target arrangement. The appliances can be generated all at the samestage or in sets or batches (e.g., at the beginning of a stage of thetreatment), or one at a time, and the patient can wear each applianceuntil the pressure of each appliance on the teeth can no longer be feltor until the maximum amount of expressed tooth movement for that givenstage has been achieved. A plurality of different appliances (e.g., aset) can be designed and even fabricated prior to the patient wearingany appliance of the plurality. After wearing an appliance for anappropriate period of time, the patient can replace the currentappliance with the next appliance in the series until no more appliancesremain. The appliances are generally not affixed to the teeth and thepatient may place and replace the appliances at any time during theprocedure (e.g., patient-removable appliances). The final appliance orseveral appliances in the series may have a geometry or geometriesselected to overcorrect the tooth arrangement. For instance, one or moreappliances may have a geometry that would (if fully achieved) moveindividual teeth beyond the tooth arrangement that has been selected asthe “final.” Such over-correction may be desirable in order to offsetpotential relapse after the repositioning method has been terminated(e.g., permit movement of individual teeth back toward theirpre-corrected positions). Over-correction may also be beneficial tospeed the rate of correction (e.g., an appliance with a geometry that ispositioned beyond a desired intermediate or final position may shift theindividual teeth toward the position at a greater rate). In such cases,the use of an appliance can be terminated before the teeth reach thepositions defined by the appliance. Furthermore, over-correction may bedeliberately applied in order to compensate for any inaccuracies orlimitations of the appliance.

In many embodiments, the orthodontic appliances provided herein includea plurality of discrete shell segments that are movable relative to eachother. Such appliances can be referred to as “segmented” orthodonticappliances. Each shell segment can be shaped to receive at least aportion of a tooth, a single tooth or a plurality of adjacent teeth. Forexample, a segment can include a portion of a tooth receiving cavity, asingle tooth receiving cavity, a plurality of tooth receiving cavities,or combinations thereof. In many embodiments, adjacent shell segmentsreceive adjacent teeth, such that the shell segments collectively covera continuous span of teeth of a single dental arch (e.g., an upper orlower arch). The separations between the shell segments can correspondapproximately to the natural separations between teeth, e.g., arelocated at or near the interproximal regions of the tooth receivingcavities.

The shell segments can be joined together by an elastic material inorder to form a single orthodontic appliance shell that receives acontinuous span of teeth. Exemplary elastic materials suitable for usewith the embodiments provided herein include but are not limited toisoprene rubber, polyurethane, copolyester, styrenic block copolymer,styrene-butadiene rubber, silicone rubber, or combinations thereof. Manydifferent configurations of the elastic material and shell segments canbe used. For example, the elastic material can include a plurality ofdiscrete portions, each attached to and coupling only a subset of theshell segments (e.g., each discrete portions joins only two, three,four, or more adjacent segments). As another example, the elasticmaterial can be a single continuous piece that is attached to andcouples all of the shell segments. The elastic material can be attachedto the shell segments at one or more discrete attachment points, or overone or more continuous attachment regions. The attachment points and/orregions can be located on any suitable portion of the shell segments,such as the buccal surface, lingual surface, occlusal surface, orcombinations thereof.

The elastic material can be deformable (e.g., by stretching,compression, bending, flexing) to allow the segments to move relative toeach other. The configuration and/or properties of the elastic materialcan influence the extent to which relative movement is possible, e.g.,constrain the direction of movement, prevent the segments from beingdisplaced more than a certain distance apart or less than a certaindistance together, etc. In many embodiments, the elastic material joinsthe shell segments so as to form a single appliance shell having ageometry corresponding to a target tooth arrangement and is configuredto resist displacement of the shell segments away from a targetarrangement. Accordingly, when the appliance is worn by a patient havinga tooth arrangement different from the target arrangement specified bythe appliance, the shell segments may be displaced away from theiroriginal positions in the target arrangement, thereby producingdeformation of the elastic material. The stiffness of the shell segmentscan be greater than the stiffness of the elastic material, such thatdeformations occur primarily in the elastic material rather than in theshell segments. For example, a shell segment can have an elastic moduluswithin a range from about 10,000 psi to about 700,000 psi, and theelastic material can have an elastic modulus within a range from about100 psi to about 8000 psi, or from about 100 psi to about 50,000 psi.The resistance of the elastic material to such deformation can generateforces that are transmitted to the underlying teeth in order to elicittooth repositioning towards the target arrangement specified by theappliance.

FIGS. 3A through 3C illustrate a segmented orthodontic appliance 300, inaccordance with many embodiments. The appliance 300 includes a pluralityof discrete shell segments 302 a, 302 b and a plurality of discreteelastic segments 304 coupled together to form a single appliance shell306. The shell segments, such as those shown as 302 a, 302 b, caninclude cavities shaped to each receive one or more of the teeth (orportions of the teeth) of a patient's dental arch. As non-limitingexamples, illustrated segments 302 b each receive a single tooth,whereas segments 302 a each span a plurality of teeth. In additionalembodiments, an orthodontic appliance can include segments spanning asingle tooth, segments spanning a plurality of teeth, as well as variouscombinations thereof. In appliance construction, segments that span asingle tooth, as well as those that span a plurality are not limited toany particular location within the arch, but the location can beselected in appliance design.

Some of the shell segments may receive a plurality of teeth (e.g., shellsegments 302 a), while others may receive a single tooth (e.g., shellsegments 302 b). In many embodiments, the shell segments 302 a, 302 breceive a continuous span of teeth and are separated from each other ator near the interproximal regions of the teeth. The elastic segments 304are interspersed between the shell segments 302 a, 302 b at or near theaforementioned interproximal regions and couple neighboring shellsegments to each other, thus forming a single appliance shell 306. Inmany embodiments, the resultant appliance shell 306 is translucent ortransparent, so as to improve the overall aesthetics of the appliance300 when worn by a patient.

The elastic segments 304 can be permanently affixed to the shellsegments 302 a, 302 b so that the shell segments 302 a, 302 b andelastic segments 304 cannot be nondestructively detached from eachother. The appliance shell 306 may be a continuous shell in which thecoupled shell segments 302 a, 302 b and elastic segments 304 are joinedwithout leaving any gaps or apertures between neighboring shellsegments. For example, the elastic segments 304 may extend across thebuccal, occlusal, and lingual surfaces of the appliance 300, thusforming a shell 306 with a continuous exterior surface. Alternatively,some of the elastic segments 304 may extend only partially across thesesurfaces (e.g., only across the buccal and lingual surfaces, only acrossthe lingual and occlusal surfaces, only across the lingual surface,etc.) such that the shell 306 includes one or more gaps or apertures inits exterior surface.

The shell segments 302 a, 302 b can be formed from relatively rigidmaterials, such that the stiffness of the shell segments 302 a, 302 b isgreater than the stiffness of the elastic segments 304. The shellsegments 302 a, 302 b can be shaped to conform to the current topographyof the patient's teeth. In such embodiments, when the shell 306 isplaced over the teeth of a patient's arch, as depicted in FIG. 3B, theshell segments 302 a, 302 b are rigidly connected to the underlyingteeth and therefore do not generate tooth repositioning forces.Conversely, the elastic segments 304 are not rigidly connected to theteeth and can therefore generate forces for eliciting movements of theunderlying teeth. At least some of these forces can be generated bydeformation (e.g., stretching) of the elastic segments 304 when theshell 306 is worn by the patient, due to intentional mismatch betweenthe geometry of the shell 306 (e.g., the spatial disposition of theshell segments 302 a, 302 b and/or elastic segments 304) and the currentarrangement of the patient's teeth. For example, when the shell 306 isworn by the patient, some of the shell segments 302 a, 302 b may bedisplaced from their original positions, thereby stretching theintervening elastic segments 304. The elastic segments 304 can bedeformed before being coupled the shell and/or before the appliance isworn by the patient, such that there is an initial “pre-loading” forceor tension in the elastics. Alternatively, the elastic segments 304 canbe relaxed prior to wearing of the appliance, such that there is nopre-loading force before the appliance is placed on the teeth. Theresistance of the elastic segments 304 to deformation may exert forceson the shell segments 302 a, 302 b that are transmitted to the teeth,thereby eliciting movements of one or more teeth with respect to up tosix degrees of freedom of motion (e.g., translation, rotation,intrusion, extrusion, tipping, torqueing, etc.). As the teeth arerepositioned, the shell segments 302 a, 302 b can return to theiroriginal positions, decreasing the extent of deformation of the elasticsegments 304 and thus reducing the forces applied to the teeth (FIG.3C).

In some embodiments, an orthodontic appliance can include a plurality ofdiscrete shell segments embedded in or coated with an elastic material,such that the elastic material substantially covers or surrounds thesegments. The shell segments include tooth receiving cavities, in asimilar manner as described in connection with other embodiments herein.The elastic material coats or surrounds the shell segments so as to holdthe segments in a desired positioning relative to other segments. Whenin use, teeth are received in the cavities of the appliance, includingthose formed by the shell segments. The elastic material may stretch ordeform to allow movement of the shell segments relative to each otherupon placement of the appliance over the patient's teeth. The stretchedor deformed elastic material can then exert forces that are transmittedto the teeth received in the shell segments.

FIG. 4 illustrates a segmented orthodontic appliance 400, in accordancewith many embodiments. Similar to the appliance 300, the appliance 400includes a plurality of discrete shell segments 402 a, 402 b, eachshaped to receive one or more teeth and separated from each other at ornear the interproximal regions. The shell segments 402 a, 402 b areembedded in a layer of elastic material 404 which surrounds the shellsegments 402 a, 402 b (e.g., coats the exterior and/or interiorsurfaces), joining them to each other at or near the interproximalregions to form a single appliance shell 406. Although the elasticmaterial 404 is depicted in FIG. 4 as covering the entire appliance 400,in other embodiments, the elastic material 404 may cover only a portionof the appliance 400, such as the portions at or adjacent to theinterproximal regions. As previously described herein, when the shell406 is worn on the patient's teeth, the elastic material 404 can exertforces that are transmitted to the underlying teeth via the shellsegments 402 a, 402 b for eliciting tooth movements. In manyembodiments, the appliance 400 enables larger tooth movements to beproduced with fewer shell segments.

Various different embodiments or configurations may be considered for anappliance having elastic material surrounding shell segments in themanner described. For example, an appliance may accommodate variousdifferent configurations for elastic materials, including differentcompositions and/or structures of elastic materials. Elastic materialforming a layer may include a single continuous layer of elasticmaterial or multiple layers of the same elastic material, differentmaterials, or a combination of some layers of the same material and oneor more layers of different material(s). Properties of the elasticmaterial layer such as resiliency, elasticity, hardness/softness, color,and the like can be determined, at least partially, based on theselected material, layers of material, and/or elastic layer thickness.In some instances, the elastic material or layer can be configured suchthat one or more properties are uniform along a length or portion of theelastic (or entire elastic). Additionally or alternatively, one or moreproperties of the elastic material or layer may vary along a length orportion of the elastic (or entire elastic). Vary (or variable) may forexample mean that the variations of the one or more properties arehigher than 10%, higher than 25%, or higher than 50% of the highestvalue of the corresponding property or properties of the elasticmaterial. For example, an elastic material or layer may havesubstantially uniform thickness along a length or portion (or entireelastic), or may vary along a length/portion (or entire elastic).Substantially uniform may mean that the variations (e.g., the absolutevalue of the difference between any two values of one property withregard to the appliance) of the one or more properties is no higher than50%, no higher than 25%, or no higher than 10% of the highest value ofthe corresponding property/properties of the elastic material. As willbe appreciated, characteristics of the elastic or layer may be selectedso as to affect the force application to the patient's teeth or toothmovement aspects of a particular treatment desired.

FIG. 5 illustrates a segmented orthodontic appliance 500 with shapememory properties, in accordance with many embodiments. The appliance500 includes a plurality of discrete shell segments 502. In manyembodiments, each shell segment 502 is shaped to receive a single tooth.In alternative embodiments, the orthodontic appliance 500 can includesegments spanning a single tooth, segments spanning a plurality ofteeth, as well as various combinations thereof. The segments 502 can becoupled to each other to form a single appliance 500 by an elasticmaterial 504, depicted in FIG. 5 as a wire. The elastic material 504 caninclude a plurality of attachment portions 506, with each portion 506being coupled to a respective segment 502, e.g., via suitable adhesiveor fastening elements 508 (depicted herein as pairs of bands). In theembodiment of FIG. 5 , the elastic material 504 has a serpentine shape,with the attachment portions 506 being located near the occlusalportions of the serpentine shape. In alternative embodiments, theelastic material 504 can be formed with other geometries, e.g., linear,arcuate, curvilinear, etc., and the location of the attachment portions506 can be varied as desired.

In many embodiments, the elastic material 504 is a material with shapememory properties, such as a shape memory wire, alloy, or polymer.Exemplary shape memory alloys include but are not limited tonickel-titanium, copper-aluminum-nickel, or combinations thereof.Exemplary shape memory polymers include but are not limited topolyurethane, epoxies, polyolefins, polyesters, or combinations thereof.The appliance 500 can be fabricated with the elastic material 504 havingan initial, undeformed geometry that places the attached shell segments502 in an arrangement corresponding to a target arrangement for thepatient's teeth. When the appliance 500 is worn by a patient,differences between the patient's current tooth arrangement and thetarget arrangement can cause displacement of the shell segments 502 andtherefore deformation of the elastic material 504 away from the initialgeometry. The elastic material 504 can be triggered to return to itsinitial geometry upon application of an appropriate shape memorystimulus (e.g., temperature change, exposure to light, application ofelectricity), which can apply forces to the shell segments 502 and teethto move the teeth towards the target tooth arrangement defined by theinitial geometry.

The appliances described herein can be used in combination with one ormore attachments mounted onto one or more of the received teeth.Accordingly, the topography of the shell segment can be modified toaccommodate the attachment (e.g., with a suitable receptacle forreceiving the attachment). The attachment can engage the shell segmentsand/or elastics to transmit repositioning forces to the underlyingteeth, as previously described herein. Alternatively or in addition, theattachment can be used to retain the appliance on the patient's teethand prevent it from inadvertently becoming dislodged. For example, teethwith no undercuts (e.g., central teeth, lateral teeth) may require anattachment to ensure correct engagement of the attachment onto theteeth, while teeth with natural undercuts (e.g., molars) may not requirean attachment. The attachment can be mounted onto any suitable portionof the tooth, such as on a buccal or lingual surface of the tooth.

The appliances described herein may apply forces to some or all of thereceived teeth. For example, as previously described herein, some of theteeth received by the appliance can serve as anchors for holding theappliance in place (e.g., teeth received by shell segments 302 a, 402a), while other teeth can be repositioned by the appliance (e.g., teethreceived by shell segments 302 b, 402 b). Furthermore, the magnitude anddirection of the forces applied to the teeth (and thus the magnitude anddirection of the resultant tooth movements) can be determined based onthe properties of the shell segments and/or elastics, such as number,geometry, configuration, and/or material characteristics, as describedin further detail herein.

FIG. 6A illustrates a method 600 for creating an orthodontic appliance,in accordance with many embodiments. The method 600 can be applied toany embodiment of the orthodontic appliances described herein. FIGS. 7Athrough 7D illustrate fabrication of an orthodontic appliance, inaccordance with many embodiments.

In step 610, a plurality of discrete shell segments are provided, eachincluding one or more cavities shaped to receive at least portions ofteeth (see, e.g., shell segments 702, 704, and 706 of FIG. 7B). Theshell segments can collectively receive a continuous span of teeth, withseparations between shell segments located at or near the interproximalregions. The number and/or shape of the shell segments can be selectedto accommodate the desired tooth movements. The shell segments can beindividually fabricated and provided as discrete components, orseparated from a larger shell as described below. Exemplary methods forfabricating shells or discrete shell segments include thermoforming,rapid prototyping, stereolithography, or computer numerical control(CNC) milling. The material of the shell or shell segments can betranslucent, such as a translucent polymer. Alternatively, the shell orshell segments can be transparent, opaque, or any other suitable levelof optical clarity. The shell or shell segments can be fabricated basedon a physical or digital model of the patient's teeth. The model can begenerated from dental impressions or scanning (e.g., of the patient'sintraoral cavity, of a positive or negative model of the patient'sintraoral cavity, or of a dental impression formed from the patient'sintraoral cavity).

In step 620, the plurality of discrete shell segments are joined usingan elastic material, thereby forming a single appliance shell. Aspreviously mentioned, the elastic material can be provided as aplurality of discrete segments (see, e.g., elastic segments 708 of FIG.7C), as a layer or coating (see, e.g., elastic layer 710 of FIG. 7D), asan elongate serpentine wire, or any other suitable configuration. Theelastic material can have varying levels of optical clarity. In manyembodiments, the elastic material is transparent, translucent, oropaque. The elastic material can be provided as wires, strips, bands,sheets, meshes, coatings, layers, or suitable combinations thereof, andcan be fabricated from any suitable material. Exemplary fabricationmethods for elastics include extrusion, rapid prototyping, spraying,thermoforming, or suitable combinations thereof. The characteristics ofthe elastic material (e.g., length, width, thickness, area, shape,cross-section, stiffness, etc.) may be homogeneous or substantiallyhomogeneous throughout the bulk of the elastic material, or may bevariable. Substantially homogeneous may mean that the variations of theone or more properties is no higher than 50%, no higher than 25%, or nohigher than 10% of the highest value of the correspondingproperty/properties of the elastic material. For example, differentportions of the elastic layer 710 may have different thicknesses (e.g.,differing by more than 10%, more than 25%, or more than 50% of themaximum thickness of the elastic layer), thereby altering the localcompliance of the appliance shell. Furthermore, in some instances, theelastic can have anisotropic characteristics. As an example, the elasticmay be relatively compliant along a first direction, and less compliant(or noncompliant) along a second direction. The directionality of theelastic can be used to control the direction of the resultant forcesapplied to the teeth. The appliances described herein may utilize asingle type of elastic, or a plurality of different types of elastics.For instance, the elastic segments 708 may have different stiffnesses,thus altering the amount of force applied to each tooth (or group ofteeth).

The elastic material can be coupled to the shell segments using suitableadhesives or bonding agents. In some instances, the elastic material mayhave adhesive properties, thus enabling the elastic to be directlycoupled to the shell segments without the use of additional externalagents. Exemplary methods of attaching the elastics to the shellsegments include extrusion, spraying, coating, dipping, gluing,thermoforming, mechanically connecting, stitching, riveting, weaving, orsuitable combinations thereof.

FIG. 6B illustrates a method 650 for creating an orthodontic appliance,in accordance with many embodiments. The method 650 can be applied toany embodiment of the orthodontic appliances described herein. In step660, a shell including one or more cavities shaped to receive at leastportions of teeth is provided (see, e.g., shell 700 of FIG. 7A). Theshell can be fabricated based on the patient's teeth and using anysuitable method, as discussed above. In step 670, the shell is separatedinto a plurality of discrete shell segments, each including one or morecavities shaped to receive at least portions of teeth (see, e.g., shellsegments 702, 704, and 706 of FIG. 7B). The number and shape of theshell segments can be selected to accommodate the desired toothmovements. In many embodiments, the shell is separated into discretesegments by cutting the shell, e.g., at or near one or moreinterproximal regions.

In step 680, the plurality of discrete shell segments are joined usingan elastic material, thereby forming a single appliance shell (see,e.g., FIGS. 7C and 7D), as previously described herein with respect tostep 620 of FIG. 6A. FIG. 7C shows an appliance including a segmentsjoined by elastic 708. FIG. 7D shows an appliance including segmentshaving a layer/coating 710 so as to join the segments. The geometry ofthe recoupled appliance shell may be different than the geometry of theinitial shell provided in step 660. For example, the geometry of theinitial shell may match the current arrangement of the patient's teeth,while the recoupled shell may match a desired tooth arrangement. Aspreviously described herein, the deliberate mismatch between the desiredand current arrangement can cause deformation of the elastics when theappliance is worn, thereby producing forces for repositioning the teethto the desired arrangement.

Appliance fabrication or design can make use of one or more physical ordigital representations of the patient's teeth. Representations of thepatient's teeth can include representations of the patient's teeth in acurrent arrangement, and may further include representations of thepatient's teeth repositioned in one or more treatment stages. Treatmentstages can include a desired or target arrangement of the patient'steeth, such as a desired final arrangement of teeth. Treatment stagescan also include one or more intermediate arrangements of teeth (e.g.,planned intermediate arrangements) representing arrangements of thepatient's teeth as the teeth progress from a first arrangement (e.g.,initial arrangement) toward a second or desired arrangement (e.g.,desired final arrangement).

FIG. 8 illustrates a method 800 for digitally planning an orthodontictreatment and/or design or fabrication of an appliance, in accordancewith many embodiments. The method 800 can be applied to any of thetreatment procedures described herein and can be performed by anysuitable data processing system.

In step 810, a digital representation of a patient's teeth is received.The digital representation can include surface topography data for thepatient's intraoral cavity (including teeth, gingival tissues, etc.).The surface topography data can be generated by directly scanning theintraoral cavity, a physical model (positive or negative) of theintraoral cavity, or an impression of the intraoral cavity, using asuitable scanning device (e.g., a handheld scanner, desktop scanner,etc.).

In step 820, one or more treatment stages are generated based on thedigital representation of the teeth. The treatment stages can beincremental repositioning stages of an orthodontic treatment proceduredesigned to move one or more of the patient's teeth from an initialtooth arrangement to a target arrangement. For example, the treatmentstages can be generated by determining the initial tooth arrangementindicated by the digital representation, determining a target tootharrangement, and determining movement paths of one or more teeth in theinitial arrangement necessary to achieve the target tooth arrangement.The movement path can be optimized based on minimizing the totaldistance moved, preventing collisions between teeth, avoiding toothmovements that are more difficult to achieve, or any other suitablecriteria.

In step 830, at least one orthodontic appliance is fabricated based onthe generated treatment stages. For example, a set of appliances can befabricated, each shaped to accommodate a tooth arrangement specified byone of the treatment stages, such that the appliances can besequentially worn by the patient to incrementally reposition the teethfrom the initial arrangement to the target arrangement. The applianceset may include one or more of the segmented appliances describedherein. The properties of the shell segments and elastics of suchsegmented appliances (e.g., number, geometry, configuration, materialcharacteristics) can be selected to elicit the tooth movements specifiedby the corresponding treatment stage. At least some of these propertiescan be determined via suitable computer software or other digital-basedapproaches. The fabrication of the appliance may involve creating adigital model of the appliance to be used as input to acomputer-controlled fabrication system.

In some instances, staging of various arrangements or treatment stagesmay not be necessary for design and/or fabrication of an appliance. Asillustrated by the dashed line in FIG. 8 , design and/or fabrication ofan orthodontic appliance, and perhaps a particular orthodontictreatment, may include use of a representation of the patient's teeth(e.g., receive a digital representation of the patient's teeth 810),followed by design and/or fabrication of an orthodontic appliance basedon a representation of the patient's teeth in the arrangementrepresented by the received representation. For example, a shell may begenerated based on the representation of the patient's teeth (e.g., asin step 810), followed by segmentation of the shell and application ofelastics to generate an appliance described in various embodimentsherein.

FIG. 9 is a simplified block diagram of a data processing system 900that may be used in executing methods and processes described herein.The data processing system 900 typically includes at least one processor902 that communicates with one or more peripheral devices via bussubsystem 904. These peripheral devices typically include a storagesubsystem 906 (memory subsystem 908 and file storage subsystem 914), aset of user interface input and output devices 918, and an interface tooutside networks 916. This interface is shown schematically as “NetworkInterface” block 916, and is coupled to corresponding interface devicesin other data processing systems via communication network interface924. Data processing system 900 can include, for example, one or morecomputers, such as a personal computer, workstation, mainframe, laptop,and the like.

The user interface input devices 918 are not limited to any particulardevice, and can typically include, for example, a keyboard, pointingdevice, mouse, scanner, interactive displays, touchpad, joysticks, etc.Similarly, various user interface output devices can be employed in asystem of the invention, and can include, for example, one or more of aprinter, display (e.g., visual, non-visual) system/subsystem,controller, projection device, audio output, and the like.

Storage subsystem 906 maintains the basic required programming,including computer readable media having instructions (e.g., operatinginstructions, etc.), and data constructs. The program modules discussedherein are typically stored in storage subsystem 906. Storage subsystem906 typically includes memory subsystem 908 and file storage subsystem914. Memory subsystem 908 typically includes a number of memories (e.g.,RAM 910, ROM 912, etc.) including computer readable memory for storageof fixed instructions, instructions and data during program execution,basic input/output system, etc. File storage subsystem 914 providespersistent (non-volatile) storage for program and data files, and caninclude one or more removable or fixed drives or media, hard disk,floppy disk, CD-ROM, DVD, optical drives, and the like. One or more ofthe storage systems, drives, etc may be located at a remote location,such coupled via a server on a network or via the internet/World WideWeb. In this context, the term “bus subsystem” is used generically so asto include any mechanism for letting the various components andsubsystems communicate with each other as intended and can include avariety of suitable components/systems that would be known or recognizedas suitable for use therein. It will be recognized that variouscomponents of the system can be, but need not necessarily be at the samephysical location, but could be connected via various local-area orwide-area network media, transmission systems, etc.

Scanner 920 includes any means for obtaining a digital representation(e.g., images, surface topography data, etc.) of a patient's teeth(e.g., by scanning physical models of the teeth such as casts 921, byscanning impressions taken of the teeth, or by directly scanning theintraoral cavity), which can be obtained either from the patient or fromtreating professional, such as an orthodontist, and includes means ofproviding the digital representation to data processing system 900 forfurther processing. Scanner 920 may be located at a location remote withrespect to other components of the system and can communicate image dataand/or information to data processing system 900, for example, via anetwork interface 924. Fabrication system 922 fabricates appliances 923based on a treatment plan, including data set information received fromdata processing system 900. Fabrication machine 922 can, for example, belocated at a remote location and receive data set information from dataprocessing system 900 via network interface 924.

As used herein A and/or B encompasses one or more of A or B, andcombinations thereof such as A and B.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. Numerous differentcombinations of embodiments described herein are possible, and suchcombinations are considered part of the present disclosure. In addition,all features discussed in connection with any one embodiment herein canbe readily adapted for use in other embodiments herein. It is intendedthat the following claims define the scope of the invention and thatmethods and structures within the scope of these claims and theirequivalents be covered thereby.

1. (canceled)
 2. An orthodontic appliance comprising: an appliance shellconfigured to reposition a patient's teeth from a first arrangementtoward a second arrangement, the appliance shell comprising: a pluralityof shell segments, wherein each shell segment comprises a first elasticmodulus, and wherein each shell segment comprises one or moretooth-receiving cavities, and a plurality of elastic segments, whereineach elastic segment comprises a second elastic modulus less than thefirst elastic modulus, wherein each elastic segment is coupled to arespective pair of adjacent shell segments, such that when the applianceshell is worn on the patient's teeth, each elastic segment is stretchedto increase a spacing between the respective pair of adjacent shellsegments, and each elastic segment resists the stretching to apply arepositioning force to teeth received by the respective pair of adjacentshell segments.
 3. The orthodontic appliance of claim 2, wherein eachelastic segment is located at an interproximal region of the applianceshell and continuously spans an occlusal, buccal, and lingual surface ofthe interproximal region.
 4. The orthodontic appliance of claim 2,wherein the stretching of each elastic segment increases aninterproximal spacing between the respective pair of adjacent shellsegments.
 5. The orthodontic appliance of claim 2, wherein each shellsegment comprises a first material having the first elastic modulus, andeach elastic segment comprises a second material having the secondelastic modulus.
 6. The orthodontic appliance of claim 5, wherein thefirst material is different from the second material.
 7. The orthodonticappliance of claim 2, wherein at least some of the plurality of shellsegments are configured to receive a single tooth.
 8. The orthodonticappliance of claim 2, wherein each elastic segment is directly coupledto the respective pair of adjacent shell segments.
 9. The orthodonticappliance of claim 2, wherein the plurality of elastic segments are aplurality of discrete elastic segments.
 10. The orthodontic appliance ofclaim 2, wherein the plurality of elastic segments are part of amaterial layer coating one or more surfaces of the appliance shell. 11.The orthodontic appliance of claim 2, wherein at least some of theplurality of elastic segments include a pre-loading force before theappliance shell is placed on the patient's teeth.
 12. A methodcomprising: determining a treatment plan for a patient's teeth, thetreatment plan comprising repositioning the patient's teeth from a firstarrangement toward a second arrangement; generating a digital model ofan appliance shell configured to reposition the patient's teeth from thefirst arrangement toward the second arrangement, wherein the applianceshell comprises: a plurality of shell segments, wherein each shellsegment comprises a first elastic modulus, and wherein each shellsegment comprises one or more tooth-receiving cavities, and a pluralityof elastic segments, wherein each elastic segment comprises a secondelastic modulus less than the first elastic modulus, wherein eachelastic segment is coupled to a respective pair of adjacent shellsegments, such that when the appliance shell is worn on the patient'steeth, each elastic segment is stretched to increase a spacing betweenthe respective pair of adjacent shell segments, and each elastic segmentresists the stretching to apply a repositioning force to teeth receivedby the respective pair of adjacent shell segments; and transmitting thedigital model to a fabrication system, wherein the fabrication system isconfigured to fabricate the appliance shell based on the digital model.13. The method of claim 12, wherein each elastic segment is located atan interproximal region of the appliance shell and continuously spans anocclusal, buccal, and lingual surface of the interproximal region. 14.The method of claim 12, wherein the stretching of each elastic segmentincreases an interproximal spacing between the respective pair ofadjacent shell segments.
 15. The method of claim 12, wherein each shellsegment comprises a first material having the first elastic modulus, andeach elastic segment comprises a second material having the secondelastic modulus.
 16. The method of claim 15, wherein the first materialis different from the second material.
 17. The method of claim 12,wherein the fabrication system is configured to fabricate the applianceshell using a rapid prototyping process.
 18. The method of claim 12,further comprising fabricating the appliance shell based on the digitalmodel.
 19. The method of claim 12, wherein each elastic segment isdirectly coupled to the respective pair of adjacent shell segments. 20.The method of claim 12, wherein the plurality of elastic segments are aplurality of discrete elastic segments.
 21. The method of claim 12,wherein the plurality of elastic segments are part of a material layercoating one or more surfaces of the appliance shell.